Combustion stabilization means having igniter grill heated by pilotburner



March 1953 w. BRZOZOWSKI 2,632,300

COMBUSTION STABILIZATION MEANS HAVING IGNITER GRILL HEATED BY PILOT BURNER 2 SHEETS-SHEET 1 Filed Aug. 3, 1949 IGN/TED FUEL A/R MIXTURE FUEL AIR STREAM a All? I FUEL I ln vemor Wi/o/d Brzozowskz Agents.

March 24, 1953 w. BRZOZOWSKI 2,632,300

COMBUSTION STABILIZATION MEANS HAVING IGNITER GRILL HEATED BY PILOT BURNER Filed Aug. 3, 1949 2 SHEETS-SHEET 2 F/ 6/2 286 lm en for /5 Wi/o/o Brzozowsh Agenfs.

Patented Mar. 24, 1953 COMBUSTION STABILIZATION MEANS-HAY- ING IGNITER- GRILL HEATED BY. PI OT:

BURNER Witold Brzoz owski, Waltham,,,Mas s.,.. assignor .to

Thermal Research &, Engineering Com Waltham, Mass e. corporation of Delaware] ApplicationAugust a, 1949, Serial No. 108,316

2 Claims-H (o1. 60:1 .93)

This invention relates to a burner, and more particularly, aburnerwherein fuel in fluid form is. mixed with a column of air movingtthere -l through under pressure, and burned therein.. The invention is especially useful in its applica tion .to jet propulsion, to whieh use,. however, it

9 est ct d V he efienwnpl cati n -e nt nu t ni nl part; of my copending application Serial No. 6 .043 5. ledF bruarr1z 1 4 m P n O- 2,6.25,

An important problem; in designing apparatus for burning fluid fuel difiused in a. column of air movingthrough a chamberor tube,,is that.

ing combustion of the fuel in a reasonable lengthv of chamber or tube. In my said copending application, Serial No. 650,305, there isdisclosed an apparatus, comprisinga tube through which air passes at high velocity. Within the tube are disposed; in order along the path of the moving aircolumn, a fuel-supplyelement, aflame preserver in the form of ashell extending transversely across=the interior of the. tube, and an igniter grill comprising a plurality. ofv substan-..

tially parallelstream-lined igniter webs extend:

ingin line across the tube each .at right angles, to the major axisof thefiame preserver, shell. The igniter webs are heated to inoandescence by. the fuelair. mixture, and in turn, spreadthe.

flame, malge possible complete combustion of the,

fuel-air mixture in a space of restricted length,

and eignite the mixture if its combustionbecomes, interupted,

I have now found that, under certair condition s, a different type of flame preserver from that disclosed in my aforesaid copending patent application may be advantageously employed. ,7 Under such conditions, I have also found it of.

advantage to employ a differentv design of igniter web, andto space and arrange theseigniter webs within the chamber or tube indifierentmanner. from that disclosedinml aforesaid copending patent application.

According to the present invention, the fuelsupply element-may. take the form ofa stream-,

, lined conduit extending. across the chamber or tubein the path of the moving column of air,

and the ou tlet of this element maybe along its downstream side, Also, in accordance withthe nv ntioni, t e .-.flame.; pr se ve-sh l m t nd; pssz he chamber; or wheat righ angl s. 1 9.1:

2. the maj or axis .of the, fuel supply. element; or, V the-flame. preserver shell may be annular in form and. disposed in the tubecoaxiallytherewith Finally, the present invention contemplates an igniter grillformedby disposit ionof the igniterlf webs ina succession o f ranlgs each in line across the chamber or tube Special designs of igniter" web 's may be, employed to advantage,"

he n e i n i ustrat d y W bf xam l e-. ce m en ine irigsy Wh h.' 1"." Fig. 1 is a broken longitudinal mid-section hrou n r nstrup ed, n rra s d e cording to the invention; Fig, 2 isa crossrsection' taken on the line II II of Fig'. 1, they section being shownonan'enlarged'. scale; big. 3 is anenlargedseetion taken on the line mf l Q v. V Fig. 4 is an enlarged perspective fragmental viewbf one of the igniter .we b s shown in 1;

Fig. 5 is a cross-section taken on the'line V .V v fFi ee ti in hqw Oe. n ree.d. scale; Fig.' 6 is 4 a, a broken I longitudinal mid-section taken on thfi line VI-VI of Big, '5. showing ii n cross-section one type. of igniter grilland one arrangement ofv a plurality of igniter webs Fig. 7 is a fragmental longitudinal mid-section through another burner v having I therein a diner ent typeof flame preserverj Fig. 8 is" a cross section talgen on the line flnlf of ig Fig. 9 is a cross section taken on, the line IXfIXY Fig.

Fig. 10 isajbroken longitudinal mid-section m lar to that 1 t @i. .d. h..F-i ei' cross-section I another type of ig n iter "grin" and one arrangement of n a plurality of jignite r web s" av n al fier nt o m'; Fig. 11 is a broken longitudinal mid-section similar to those illustra 'zed infFijg's. ef'andioj showing another type of V igniter grill I arrangment, the igniter webs which form the grill hayingthe form of those shqwnin Fig. 10; Fig 12 is a cross-seetion through Ta single, igniter web of a different type from those unis trated inFigs 6,, 10 and11.; and Fig, 13 is a cross-section through an igniter. web of still a different vtype. Referring new tothe drawings, and particularly to the, embodiment. illustrated inv Figs 1, to 6 inclusive, there is prdyideda charnb er, here.-v shown as a 1 tube I 5,, through ,which a column of airis moved athighwelocity. In order tol form}.

he-merger. were r isnees w nial' ha iibe;

3 l5 in downstream succession, a fuel supply element IS, a flame preserver I1, and an igniter grill 18.

The fuel-supply element comprises a streamlined conduit extending transversely within the tube I5. A pipe l9 suitably coupled, as at 20, to the fuel-supply element, carries thereto a fluid fuel which is discharged into the moving air column through a constricted opening 2| extending longitudinally of the element along its downstream side. Since the fuel is discharged into the moving air column substantially completely across the tube l5, diametrically thereof, the fluid fuel is diflused within the moving column of air to provide a fuel-air mixture, which continues to move along the tube [5 at a high velocity.

Within the chamber, or tube l5, downstream from the fuel-supply element It and extending transversely of the tube, is positioned the flame preserver 11. Because the velocity of the fuel-air mixture may be greater than the rate of flame propagation, the flame preserver I! is designed to emit a flame continuously for constantly igniting combustion of the fuel-air mixture therein, unless special provision were made for spreading the flame at a point near the burner.

Accordingly, the edges 25 of the longitudinal exit opening 23 may be spread apart to reduce the velocity of the fuel-air mixture immediately adjacent the downstream openin 23, and thus to widen the ignition wedge at the flame preserver. Such arrangement is shown in Fig. 1. Furthermore, and of greater importance, the igniter grill i8 is positioned in the path of the ignition wedge to receive heat from the burning fuel-air mixture and to transfer such heat outwardly in the igniter webs 26, positioned in the tube [5 at right.

angles to the longitudinal axis of the flame preserver, with their heads 21 toward the oncoming fuel-air mixture.

Although the heads 21 of the T-shaped igniter webs 26 are shown as being continuous, such is not necessarilythe case. The igniter webs here shown are positioned in successive ranks, each rank comprising a plurality of webs in parallel spaced relationship across the tube. Three such ranks are illustrated in Fig. 6, although more or fewer may be employed. Accordingly, when the ignited fuel-air mixture 7 meets the first rank of igniter webs, it impinges taposed holes or orifices. Thus the fuel-air mixture passing through the longitudinal opening 22 in the flame preserver has its velocity materially decreased as it enters the protected and comparatively quiet area within the unit, The longitudinal opening 23 on the downstream side of the flame preserver permit the ignited fuel-air mixture to leave the burner and to enter the moving unignited fuel-air mixture column beyond the burner. The cross-section of the longitudinal opening 22 is so related to the volume within the burner that the flame will not be blown out by the rapidly moving mixture external to the flame preserver. Igniting means is provided within the unit. Thus, in the illustrated embodiment, a spark plug 24 projects through the tube l5'and into one end of the flame preserver I! for igniting the fuel-air mixture therein.

Because of the reduced velocity of the fuel-air mixture within the flame preserver, it is possible to maintain combustion therein continuously despite the high velocity of the external fuel-air mixture. Consequently, the ignited fuel-air mixture which leaves the flame preserver through its downstream longitudinal exit opening or slot 23 mixes with the unignited fuel-air mixture and constantly serves to ignite it across the diameter of the tube.

As indicated by the dot-dash lines in Fig. l, the flame issuing in a ribbon from the downstream longitudinal opening 23 across the width of the burner, expands in wedge formation as the fuelupon the heads of the T-shaped webs, heating the webs to incandescence. The heat received by each head is conducted outwardly from the central portion of the head into the path of the unignited fuel-air mixture, which it ignites. The tail 28 of the T-shaped web 26 is protected by its head 21 from the cooling action of the unignited fuel-air mixture which strikes the web. The tail, therefore, acts efficiently to conduct heat away from the center of the web and to ignite the unair mixture is progressively ignited. Because of g ignited mixture which comes in contact with it. The successive ranks of webs act similarly. Also, the T-shaped igniter web increases the boundary layer of both ignited and unignited fuel-air mixture in contact with the web. In other words, a

greater surface of the fuel-air mixture column meets the surface of the igniter web than would be the case if it were of stream-lined shape, and the effectiveness of the web is thus increased by its shape. Accordingly, the entire fuel-air mixture may be ignited considerably nearer to the flame preserver [1 than would otherwise be the case, and a shorter tube I 5 suffices to effect complete combustion of the mixture.

It is further noted that, if for any reason surges of pressure or of flame occur in the tube, the igniter grill will act to maintain continuing combustion.

Applicant's invention is not limited to a flame preserver comprising a cylindrical shell and extending diametrically across the tube I5. Another type of flame preserver which has been operated successfully is illustrated in Figs. '7, 8 and 9. This unit Ha is constructed in the form of a hollow annulus, and is disposed concentrically within the tube 15 where it is supported as by fins 2 9. The flame preserver Ila has a narrow circular entrance opening or slot 22a in its upstream side and a similar circular exit opening or slot 23a in its downstream side, and spacers 30 within the unit may serve to hold its two annular parts to a gether; The edges '25wof the exit opening or'slot 23a are preferably spread apart in the same manner and for thesame-purpose as the edges 25 illustrated in Fig; 1. Thus an expanding ring of burning fuel-air mixture leaves the annular flame preserver m1 and tends to ignite a large propor-" tion of the unignited fuel-air mixture in the im-- mediate vicinity of the unit.

Nonetheless, it is found'desirable'to employ an igniter grill downstream-Within the-tube--l5 from-the flame preserver 11a, in order tokeep" the necessary length of the tube ata-minimum.

It isalso noted that the invention contemplates" igniter grills which are formed of webs differ ing from the T-shaped igniter websillustrated in Figs. 1, 4, 5 and 6. Thus, in the embodiment illustrated in Fig. 10, the igniter-webs'are formed as plane plates-26a disposed inparallel spaced relationship across'the tube and positioned in successiveranks'along the tube 15. Fig. ll'illustrates another arrangement of plane-plates inwhichthe individual webs are symmetrically? spacedin successive ranks which define-a V- formation. Thus, whether headed or not, the individual webs are positioned with edges thereof directed'toward the oncoming fuel-air mixture:

Instead of'employing the continuous T-forma tion of the igniter webs 26 illustrated in Figs. '1; 4, 5 and 6, the webs maybe formed in'two parts as 'illustr'atedini Fig; 12. Such webs are'formed with their heads '2': completely separated'from their tails 280, the headand' tail of eachweb being positioned in T'-formation within the tube IS'in'the manner illustrated'in Fig. 6. The advantage-of this arrangement is that the tailsare not cooled'by the heads which'are in contact withthe' unignited fuel-airmixture'. The sep arate tails 28c'may, therefore, attain and conduct'to" the unignited mixture a higher'degree of heat than ispossible in the webs 25. The head 210 of such a web is alone cooled by the unignited' fuel-air 'mixture' which impinges upon it, and the tail 28c'is completely'heated by the burning mixture with which it comes in" contact. Moreefficien't operation of theitail in spreading the flame is accordingly effected. Furthermore, theboundary layer of both ignited and unignited fuel-air mixture in contact with the web is increasedb'y'this construction'as explained above.

Still "a difierent' construction is illustrated in thermore; the particular forms of the invention.

here" described and illustrated in the accom panying drawings are presented merely as examples'of how the invention 'may be applied. Other forms, embodiments andapplications' of theinvention, coming within the proper scope of theappended claims, will readily suggest" themselves to those-skilled in the burner art.

I claim':

1-." A burner for burning a column of a-"fuel-air An igniter web of this form increases 6? mixture moving at high velocity, zsaidiiburner comprising a tube through: whichra: column: 01:1 air passes; a fuel-supply-relementin saidsitubee for diffusingfuel :intothe column .of 1 airtstocproay.

; videa fuel-air mixture; afiame preservermithine.

said 7 tube downstream' fromsaid fuelesupplyfzele-i v ment for continuously igniting. thexfueL-airzmix-r. ture; and I a: plurality of separate. parallel iige. 1 niter'webs disposed downstream from, said. flame i preserverin a -succession 1 ofsranks 1 eachin: line extending transversely completely I across :said tuba-said webs bein formed with heads'directedtoward the oncoming 'fuel-airmixtureain: aid tube toincrease the --b'oundary.- layer of both:-

ignited and unignited fuel-air mixture in con! tact therewith and acting toreceive heatsfrom the burning fuel-air mixture and to: give :-:up heat to ignite the unignited fuel-air mixture-"e adjacent said webs.

2. Alburner :for burninga column of: Ifuelaim mixture moving athigh velocity, :said. burner; comprising a tube through: which a colum-n of i air passes; a-fuel-su-pply element in'said tube for diffusing fuel into the column of 'air:to:pro-= vide a fuel-air mixture; a flame preserverwithinw.

said tube downstream "from said fuelsupply element for continuously igniting the fuel-airmix ture; and a pluralityof T-shaped igniter webs disposed downstream from said flame .preserver=- in substantially parallel" spaced relationship across said tube, said T'-shaped web'sbeing po-- sitioned with their heads upstream to 1 protect their tails by their heads from being cooled by" the unignitedfuel-air mixture-adjacent said web's;- 3.- A'- burnerfor burning acolumn" of fuel-air" mixture moving at" high velocity; said burner comprising a tube through' which'" a "column" of air passes a fuel-supply element insaid tube for diffusing-fuel intothecolumn of air to provide a fuel-air mixture; a flame preserver'within said tube downstream from said fuel-supply element' for continuously igniting the fuel-air mixture; said flame preserver having a narrow-entrance=* slot omits-upstream side-and a simi-lar exit slot on its downstream= side, the edges" of the exit slot of said flame preserver 'beingspread apart" outwardly of said flame preservenganda-plurality of T- sh'aped igniter--webs disposed'rdown stream from" said flame preserver in substan tially parallel spaced relationship across) said tube, said T-shaped' web's beingpositioned with" theinheads upstream toprotect-theirtails by their heads frombeing "cooled" by the uni'gnited" fuel-air mixture adjacent said web's;

4; A burner for-burning a" column'of a fuelair mixture moving" at a high'velocity;v said" burner comprising a tubethrough which a column of air passes; a'fuel supply element'in-said tube for difiusing fuel into' the column ofair'to'proe vide a fuel-air mixture; a flame preserverwithim said tube downstream from said fuel-supply ele; ment for continuously igniting *the' fuel-air mix; ture, said flame'preservercomprising a hollow substantially" annular unit' disposed within said 1 tube" concentrically therewith having a. narrow circularslot on its upstreamside-anda' similar slot on its downstream side;-and aplura'lityof parallel igniter= webs disposed downstream-fromsaid flame preservei each web extending transversely completely across-said tube, said web'sbeing disposed in a=- succession 'of' ranks each in line across said tube; said webs acting to receiveheat' from the burning fuel-air 'mixtureand togive up heat to 1 ignite L the unignite'd" fuel-air;-

mixturei adj aeent said websa 5. A burner for burning a column of a fuelair mixture moving at high velocity, said burner comprising a tube through which a column of air passes; a fuel-supply element in said tube for diffusing fuel into the column of air to provide a fuel-air mixture; a flame preserver within said tube downstream from said fuel-supply element for continuously igniting the fuel-air mixture, said flame preserver comprising a hollow substantially annular unit disposed within said tube concentrically therewith having a narrow circular slot on its upstream side and a similar slot on its downstream side, and a spark plug extending through said tube into said flame preserver for igniting therein the fuel-air mixture entering said flame preserver through its upstream slot; and a plurality of parallel igniter webs disposed downstream from said flame preserver, each web extending transversely completely across said tube, said webs being disposed in a succession of ranks each in line across said tube, said webs acting to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

6. A burner for burning a column of a fuel-air mixture moving at high velocity, said burner comprising a tube through which a column of air passes; a fuel-supply element in said tube for diffusing fuel into the column of air to providea fuel-air mixture; a flame preserver within said tube downstream from said fuel-supply element for continuously igniting the fuel-air mixture, said flame preserver comprising a hollow substantially annular unit disposed within said tube concentrically therewith having a narrow circular slot on its upstream side and a similar slot on its downstream side, and a spark plug extending through said tube and into said flame preserver for igniting therein the fuel-air mixture entering said flame preserver through its narrow upstream slot; and aplurality of T- shaped igniter webs disposed downstream from said. flame preserver in substantially parallel spaced relationship across said tube, said T- shaped Webs being positioned with their heads upstream to protect their tails from being cooled by the unignited fuel-air mixture, and said webs acting to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

7. A burner for burning a column of fuel-air mixture moving at high velocity, said burner comprising a chamber through which a column of air passes; a fuel-supply element in said chamber for diffusing fuel into the column of air to provide a fuel-air mixture; a flame preserver within said chamber downstream from said fuelsupply element for continuously igniting the fuelair mixture, said flame preserver comprising a hollow substantially annular unit disposed within said chamber in the path of the unignited fuelair mixture having a narrow circular slot on its upstream side and a similar slot on its downstream side; and a plurality of T-shaped igniter webs disposed downstream from said flame preserver in substantially parallel relationship across said chamber in the path of the ignited and unignited fuel-air mixture, said webs being positioned with their heads upstream to protect their tails from being cooled by the unignited fuel-air mixture, the tails of said T-shaped igniter webs being separated from the heads thereof to prevent direct conduction of heat from the tails by the heads of said webs, and said webs acting to receive heat from the burning fuelair mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

8. A burner for burning a column of a fuelair mixture moving at high velocity, said burner comprising a tube through which the air passes; a fuel-supply element in said tube for diffusing fuel into the column of air to provide a fuel-air mixture; a flame preserver within said tube downstream from said fuel-supply element for continuously igniting the fuel-air mixture, said flame preserver comprising a hollow substantially annular unit disposed within said tube concentrically therewith having a narrow circular slot on its upstream side and a similar slot on its downstream side; and a plurality of T-shaped igniter webs disposed downstream from said burner in substantially parallel spaced relationship across said tube, said webs being positioned with their heads upstream to protect their tails from being cooled by the unignited fuel-air mixture, the tails of said T-shaped igniter webs being separated from the heads thereof to prevent direct conduction of heat from the tails by the heads of said webs, and said webs acting to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

9. A burner for burning a column of a fuelair mixture moving at high velocity, said burner comprising a tube through which a column of air passes; a fuel-supply element in said tube for difiusing fuel into the column of air to provide a fuel-air mixture; a flame preserver within said tube downstream from said fuel-supply element for continuously igniting the fuel-air mixture, said flame preserver comprising a hollow substantially annular unit disposed within said tube concentrically therewith having a narrow circular entrance slot on its upstream side and a similar exit slot on its downstream side, the exit slot of said flame preserver having its edges spread apart outwardly, and a spark plug extending through said tube and into said flame preserver for igniting therein the fuel-air mixture entering said flame preserver through its upstream slot; and a plurality of T-shaped igniter webs disposed downstream from said flame preserver in substantially parallel spaced relationship across said tube in the path of the ignited and unignited fuel-air mixture, said T- shaped webs being positioned with their heads upstream to protect their tails from being cooled by the unignited fuel-air mixture, and said webs acting to receive heat from the burning fuel-air mixture, and to give up heat to ignite any unignited fuel-air mixture adjacent said webs.

10. In a burner for burning a fuel-air mixture moving at high velocity through a chamber and having a flame preserver within the chamber for continuously igniting the fuel-air mixture:

a plurality of T-shaped igniter webs disposed downstream from the flame preserver across the chamber in the path of the ignited and unignited iuel-air mixture, said webs acting to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

11. In a burner for burning a column of a fuelair mixture moving at high velocity which comprises a chamber through which the air passes, a fuel-supply element in the chamber for difiusing fuel within the column of air to provide a fuel-air mixture, and a flame preserver within the chamber downstream-from the fuel-supply element for continuously igniting the fuel-air mixture: a plurality of T-shaped igniter webs disposed downstream from the flame preserver in a succession of ranks each in line across the chamber in the path of the ignited and unignited fuel-air mixture, said webs acting to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

12. A burner for burning a column of fuel-air mixture moving at high velocity, said burner comprising a chamber through which a column of air passes; a fuel-supply element in said chamber for diffusing fuel into the column of air to provide a fuel-air mixture; a flame preserver within said chamber downstream from said fuelsupply element for continuously igniting the fuelair mixture; and a plurality of separate parallel igniter webs disposed downstream from said preserver in a succession of ranks each in line extending transversely completely across said chamber, said Webs being positioned with their 10 major cross-sectional dimensions extending in substantial alignment with the direction of the combustion stream to receive heat from the burning fuel-air mixture and to give up heat to ignite the unignited fuel-air mixture adjacent said webs.

WITOLD BRZOZOWSKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,574,545 Bear Feb. 23, 1926 1,839,880 Hyatt Jan. 5, 1932 2,142,601 Bleecker Jan. 3, 1939 2,410,881 Hunter Nov. 12, 1946 FOREIGN PATENTS Number Country Date 384,939 France Feb. 21, 1908 

